1. Field of the Invention
The present invention relates to an RJ modular connector, and more particularly to an RJ modular connector having a printed circuit board (PCB) provided therein to reduce crosstalk between terminals.
2. Description of Related Art
RJ modular connector has been widely used in telecommunication system since it was firstly created. A so-called RJ45 modular connector is a typical example for this kind of connector.
The RJ45 modular connector includes a total of eight terminals. Resulting from miniaturization of the computer, all corresponding components, including connectors, have to be reduced as to their dimension and size. One of the negative consequences or problems created from miniaturization is crosstalk between terminals. When the RJ connector is used in low speed signal transmission, the crosstalk between adjacent terminals can be ignored in light of its effect. However, when the RJ connector is used for high-speed signal transmission, the crosstalk between adjacent terminals creates a great problem. Unless the crosstalk can be effectively controlled within an accepted level, it is unlikely that the RJ 45 modular connector can be used in the high-speed signal transmission.
One of the approaches is to select a pair of terminals as a differential pair. In the differential pair, two terminals transmit the same signal of opposite polarity. By this arrangement, a majority of the noise received between the two terminals of a differential pair can be subtracted in a data processing unit.
There are at least eight different standards having reference in selecting terminals as differential pairs namely T568A, T568B, USOC 4-pair, USOC 1-, 2- or 3-pair, 10BASE-T (802.3), Token Ring (802.5), 3-pair (MMJ), and TP-PMD (X3T9.5) and ATM. In each implementation, two terminals are selected as a pair in which some are close to each other, while some are apart from each other. Each pattern has its own uniqueness, while each also carries a crosstalk issue that needs to be solved.
Among those standards, T568A and T568B are widely used and in T568A, terminals 1, 2 configure 3rd pair, terminals 3, 6 configure 2nd pair, terminals 4, 5 configure 1st pair, while terminals 7, 8 configure 4th pair. In T568B, terminals 1, 2 configure 2nd pair, terminals 3, 6 configure 3rd pair, terminals 4, 5 configure 1st pair, while terminals 7, 8 configure 4th pair.
Since those eight terminals are equally spaced, electrical capacitances between terminals will surely create some problems, i.e. crosstalk. For example, terminal 3 will naturally pick up energy induced from terminals 2 and 4 which are close to terminal 3. On the other hand, terminal 6, which carries signal having inverted phase of the signal carried by terminal 3, will also pick up energy induced from terminals 5 and 7. However, energy induced into terminals 3, 6 from terminals 2 and 7 can not be suitably eliminated because terminals 3, 6 is unlikely to establish equal capacitances between terminal 1 and terminal 8 to balance the capacitances between terminals 2, 3 and 6, 7. Accordingly, signals transmitted by terminals 3, 6 carry noises generated by their adjacent terminals 2, 7. In addition, terminals 3 and 6 will also carry noises induced thereto from terminals 4, 5 and which capacitances should be also carefully taken to avoid certain noises.
In order to decrease the effects of electrical capacitance between the (3rd, 4th) and (3rd, 2nd) terminals, and (6th, 5th) and (6th, 7th) terminals, many approaches have been provided, such as creating electrical capacitances between 3rd and 1st terminals and 3rd and 5th terminals, to balance the electrical capacitance between the 3rd and 2nd terminals and 3rd and 4th terminals, and creating electrical capacitance between 6th and 8th terminals and 6th and 4th terminals to balance the electrical capacitances between the 6th and 7th terminals and 6th and 5th terminals.
To solve the above issue, the terminals should be rearranged or new electrical capacitances should be added.
one known solution is to have 6th and 2nd terminals arranged in the first layer, while 8th, 5th, 4th, and 1st terminals are arranged in the second layer, and 7th and 3rd terminals are arranged in the third layer.
The 6th terminal in the first layer has a rectangular loop having its longitudinal sides aligned with terminals 4th and 8th located in the second layer, while terminal 3 in the third layer also has a rectangular loop having its longitudinal sides aligned with terminals 5th and 1st located in the second layer.
In addition, the right longitudinal loop side of the terminal 6th further includes a square corresponding to a square formed in terminal 4th. The left longitudinal loop side of the terminal 3 includes also a square with respect to the square formed on terminal 5th.
The above arrangements are to increase the capacitances between (1st, 3rd), (3rd, 5th), and (4th, 6th), (6th, 8th) terminals thereby helping to balance electrical capacitances of the terminals.
However, those eight or four sets of terminals are arranged in three different layers, and each set of terminals are separately divided by an insulative sheet material. U.S. Pat. No. 5,769,647 of Tulley et al. discloses such structure. This will no doubt increase the complexity of the connector.
In addition, there are different shapes and configurations among those eight terminals. Each terminal has its own shape which is different from each other, especially the 3rd and 6th terminals, each including the rectangular loop portion which overlaps to corresponding terminals to create desired electrical couplings. Each loop further forms the square to increase the electrical capacitances with corresponding terminals having the square. The electrical capacitances created can help to meet higher system requirements. The eight different configurations of the terminals will surely increase the difficulty and complexity in production.
There are some other approaches that include routing terminal tails of those 3rd, 6th and 4th, 5th terminals to alter their position and affect capacitances between 3rd, 2nd and 3rd, 4th; and 6th, 5th, and 6th, 7th terminals. However routing terminal tails will inevitably increase the manufacturing cost.
U.S. Pat. No. 6,120,329 of Steinman discloses another approach to solve the above-addressed problem. Again, terminals are configured with different shapes and dimensions making the production complex.
U.S. Pat. No. 5,069,641 of Sakamoto et al. discloses a suggestion of using substrate in the RJ modular housing; however, it addresses different issues.
A first object of this invention is to provide an RJ modular connector, and more particularly to an RJ modular connector having a printed circuit board (PCB) with conductive traces thereon to reduce crosstalk between contacts thereof.
A second object of this invention is to provide a method of manufacturing the above RJ modular connector.
A third object of the present invention is to provide a method of reducing crosstalk between contacts of an RJ modular connector.
To obtain the above objects, an RJ connector includes an insulative housing and a contact insert attached to the housing. The contact insert includes eight signal contacts and two grounding contact arranged side by side and an upper printed substrate and a lower printed substrate sandwiching the signal contacts and the grounding contacts therebetween. There is a grounded conductive material between at least two selected adjacent signal contacts for reducing capacitance between the two selected adjacent signal contacts.
As a second aspect of this invention, at least one selected signal contact is severed into pieces and two of the pieces are re-routed by conductive traces on a printed circuit board (PCB) but adjacent contacts are not severed. Therefore, length inducing electrical capacitance between the severed contact and the adjacent contacts can be reasonably reduced, thereby reducing crosstalk between the severed contact and the adjacent contacts.
As a third aspect of this invention, at least one selected signal contact is severed into three pieces and two end portions of the pieces are re-routed by conductive traces on a printed circuit board (PCB) and the middle portion is connected to a grounding trace. Therefore, the middle portion can provide grounding contact function to the severed and the adjacent signal contacts, thereby reducing crosstalk between the severed contact and the adjacent contacts.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings.